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In
vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia artēria'' 'windpipe' + φυτά ''phutá'' 'plants'), form a large group of plants ( 300,000 ...
s, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the surface of the
soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, comp ...

soil
, but roots can also be
aerial
aerial
or aerating, that is, growing up above the ground or especially above water.


Function

The root's major functions are
absorption of waterIn higher plants water is absorbed through root hairs which are in contact with soil water and from a root hair zone a little the root tips Active absorption Active absorption refers to the absorption of water by roots with the help of adenosine t ...
and
plant nutrition Plant nutrition is the study of the chemical elements and Chemical compound, compounds necessary for plant growth, plant metabolism and their external supply. In its absence the plant is unable to complete a normal life cycle, or that the element i ...
and anchoring of the plant body to the ground.


Anatomy

Root morphology is divided into four zones: the root cap, the apical meristem, the elongation zone, and the hair. The
root cap Root tip magnified 100×. 1. Meristem 2. Columellae (statocytes with statolithes) 3. Lateral part of the tip 4. Dead cells 5. Elongation zone The root cap is a type of tissue at the tip of a plant root In vascular plants, the roots are the plant ...
of new roots helps the root penetrate the soil. These root caps are sloughed off as the root goes deeper creating a slimy surface that provides lubricant. The
apical meristem The meristem is a type of tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa dub ...
behind the root cap produces new root cells that elongate. Then, root hairs form that absorb water and mineral nutrients from the soil. The first root in seed producing plants is the
radicle Image:Salix scouleriana.seed.jpg, 250px, seed of Scouler's willow (''Salix scouleriana'') In botany, the radicle is the first part of a seedling (a growing plant embryo) to emerge from the seed during the process of germination. The radicle is the ...
, which expands from the plant embryo after seed germination. When dissected, the arrangement of the cells in a root is
root hair Root hair, or absorbent hairs, are outgrowths of epidermal cells, specialized cells at the tip of a plant root In vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τρα ...
,
epidermis The epidermis is the outermost of the three layers that comprise the skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of animal Animals (also calle ...
,
epiblem In botany, epiblem is a tissue that replaces the epidermis (botany), epidermis in most roots and in stems of submerged aquatic plants. It is usually located between the epidermis and Cortex (botany), cortex in the root or stem of a plant. Referen ...
,
cortex Cortex or cortical may refer to: Science Anatomy * Cortex (anatomy), the outermost or superficial layer of an organ * Cortex (hair), the middle layer of a strand of hair * Adrenal cortex, the portion of the adrenal gland that produces cortisol and ...
,
endodermis The endodermis is the central, innermost layer of cortex in land plants The Embryophyta () or land plants are the most familiar group of green plants that form vegetation on earth. Embryophyta is a clade A clade (; from grc, , ''klados'' ...
,
pericycle The pericycle is a cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants. Although it is composed of non-vascular parenchyma cells, it's still considered part of the ...
and, lastly, the
vascular tissue Vascular tissue is a complex conducting tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North Ameri ...
in the centre of a root to transport the water absorbed by the root to other places of the plant. Perhaps the most striking characteristic of roots that distinguishes them from other plant organs such as stem-branches and leaves is that roots have an ''endogenous'' origin, ''i.e.'', they originate and develop from an inner layer of the mother axis, such as
pericycle The pericycle is a cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants. Although it is composed of non-vascular parenchyma cells, it's still considered part of the ...
. In contrast, stem-branches and leaves are ''exogenous'', ''i.e.'', they start to develop from the cortex, an outer layer. In response to the concentration of nutrients, roots also synthesise
cytokinin Image:Zeatin.png, 122px, The cytokinin zeatin is named after the genus of corn, ''Teosinte, Zea''. Cytokinins (CK) are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in ...
, which acts as a signal as to how fast the shoots can grow. Roots often function in storage of food and nutrients. The roots of most vascular plant species enter into symbiosis with certain
fungi A fungus (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full ...

fungi
to form
mycorrhiza A mycorrhiza (from Ancient Greek, Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, mycorrhiza or mycorrhizas) is a mutual symbiosis, symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role ...

mycorrhiza
e, and a large range of other organisms including
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
also closely associate with roots.


Root system architecture (RSA)


Definition

In its simplest form, the term root system architecture (RSA) refers to the spatial configuration of a plant's root system. This system can be extremely complex and is dependent upon multiple factors such as the species of the plant itself, the composition of the soil and the availability of nutrients. Root architecture plays the important role of providing a secure supply of nutrients and water as well as anchorage and support. The configuration of root systems serves to structurally support the plant, compete with other plants and for uptake of nutrients from the soil. Roots grow to specific conditions, which, if changed, can impede a plant's growth. For example, a root system that has developed in dry soil may not be as efficient in flooded soil, yet plants are able to adapt to other changes in the environment, such as seasonal changes.


Terms and components

The main terms used to classify the architecture of a root system are: All components of the root architecture are regulated through a complex interaction between genetic responses and responses due to environmental stimuli. These developmental stimuli are categorised as intrinsic, the genetic and nutritional influences, or extrinsic, the environmental influences and are interpreted by
signal transduction pathways Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation residue Protein phosphorylation is a reversible post-translational ...

signal transduction pathways
. Extrinsic factors affecting root architecture include gravity, light exposure, water and oxygen, as well as the availability or lack of nitrogen, phosphorus, sulphur, aluminium and sodium chloride. The main hormones (intrinsic stimuli) and respective pathways responsible for root architecture development include:


Growth

Early root growth is one of the functions of the apical meristem located near the tip of the root. The meristem cells more or less continuously divide, producing more meristem,
root cap Root tip magnified 100×. 1. Meristem 2. Columellae (statocytes with statolithes) 3. Lateral part of the tip 4. Dead cells 5. Elongation zone The root cap is a type of tissue at the tip of a plant root In vascular plants, the roots are the plant ...
cells (these are sacrificed to protect the meristem), and undifferentiated root cells. The latter become the primary tissues of the root, first undergoing elongation, a process that pushes the root tip forward in the growing medium. Gradually these cells differentiate and mature into specialized cells of the root tissues. Growth from apical meristems is known as primary growth, which encompasses all elongation. Secondary growth encompasses all growth in diameter, a major component of
woody plant A woody plant is a plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, ca ...
tissues and many nonwoody plants. For example, storage roots of
sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledon The dicotyledons, also known as dicots (or more rarely dicotyls), are one of the two groups into which all the flowering plant The flowering plants, also known as Angio ...

sweet potato
have secondary growth but are not woody. Secondary growth occurs at the lateral meristems, namely the
vascular cambium The vascular cambium is the main growth tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ...
and
cork cambium Cork cambium (pl. cambia or cambiums) is a tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North Americ ...
. The former forms secondary xylem and secondary phloem, while the latter forms the
periderm Bark is the outermost layers of stems and root In vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia artēria'' 'windpipe' + ...
. In plants with secondary growth, the vascular cambium, originating between the xylem and the phloem, forms a
cylinder A cylinder (from ) has traditionally been a Solid geometry, three-dimensional solid, one of the most basic of curvilinear geometric shapes. Geometrically, it can be considered as a Prism (geometry), prism with a circle as its base. This traditi ...

cylinder
of tissue along the
stem Stem or STEM may refer to: Biology * Plant stem, the aboveground structures that have vascular tissue and that support leaves and flowers ** Stipe (botany), a stalk that supports some other structure ** Stipe (mycology), the stem supporting the c ...

stem
and root. The vascular cambium forms new cells on both the inside and outside of the cambium cylinder, with those on the inside forming secondary xylem cells, and those on the outside forming secondary phloem cells. As secondary xylem accumulates, the "girth" (lateral dimensions) of the stem and root increases. As a result, tissues beyond the secondary phloem including the epidermis and cortex, in many cases tend to be pushed outward and are eventually "sloughed off" (shed). At this point, the cork cambium begins to form the periderm, consisting of protective
cork Cork or CORK may refer to: Materials * Cork (material), an impermeable buoyant plant product ** Cork (plug), a cylindrical or conical object used to seal a container ***Wine cork Places Ireland * Cork (city) ** Metropolitan Cork, also known as G ...
cells. The walls of cork cells contains
suberin Suberin, cutin and lignins are complex, higher plant Epidermis (botany), epidermis and periderm cell-wall macromolecules, forming a protective barrier. Suberin, a complex polyester biopolymer, is lipophilic, and composed of long chain fatty acids ...

suberin
thickenings, which is an extra cellular complex biopolymer. The suberin thickenings functions by providing a physical barrier, protection against pathogens and by preventing water loss from the surrounding tissues. In addition, it also aids the process of wound healing in plants. It is also postulated that suberin could be a component of the apoplastic barrier (present at the outer cell layers of roots) which prevents toxic compounds from entering the root and reduces radial oxygen loss (ROL) from the
aerenchyma alt=Aerenchyma of '' Aerenchyma in stem cross section of a typical wetland plant. Aerenchyma or aeriferous parenchyma is a spongy tissue that forms spaces or air channels in the leaves, stems and roots of some plants, which allows exchange of gases ...
during waterlogging. In roots, the cork cambium originates in the
pericycle The pericycle is a cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants. Although it is composed of non-vascular parenchyma cells, it's still considered part of the ...
, a component of the vascular cylinder. The vascular cambium produces new layers of secondary xylem annually. The xylem vessels are dead at maturity but are responsible for most water transport through the vascular tissue in stems and roots. Tree roots usually grow to three times the diameter of the branch spread, only half of which lie underneath the trunk and canopy. The roots from one side of a tree usually supply nutrients to the foliage on the same side. Some families however, such as
Sapindaceae The Sapindaceae are a family (biology), family of flowering plants in the order Sapindales known as the soapberry family. It contains 138 genera and 1858 accepted species. Examples include Aesculus, horse chestnut, maples, ackee and lychee. The ...
(the
maple ''Acer'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscr ...

maple
family), show no correlation between root location and where the root supplies nutrients on the plant.


Regulation

There is a correlation of roots using the process of plant perception to sense their physical environment to grow, including the sensing of light, and physical barriers. Plants also sense gravity and respond through auxin pathways, resulting in
gravitropism Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all ...
. Over time, roots can crack foundations, snap water lines, and lift sidewalks. Research has shown that roots have ability to recognize 'self' and 'non-self' roots in same soil environment. The correct environment of
air File:Atmosphere gas proportions.svg, Composition of Earth's atmosphere by volume, excluding water vapor. Lower pie represents trace gases that together compose about 0.043391% of the atmosphere (0.04402961% at April 2019 concentration ). Number ...

air
, mineral
nutrients A nutrient is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition * Matter, anything that has mass and ta ...
and
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...

water
directs plant roots to grow in any direction to meet the plant's needs. Roots will shy or shrink away from dry or other poor soil conditions.
Gravitropism Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all ...
directs roots to grow downward at
germination Germination is the process by which an organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biolog ...

germination
, the growth mechanism of plants that also causes the shoot to grow upward. Research indicates that plant roots growing in search of productive nutrition can sense and avoid soil compaction through diffusion of the gas
ethylene Ethylene (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Science C ...

ethylene
.


Shade avoidance response

In order to avoid shade, plants utilize a shade avoidance response. When a plant is under dense vegetation, the presence of other vegetation nearby will cause the plant to avoid lateral growth and experience an increase in upward shoot, as well as downward root growth. In order to escape shade, plants adjust their root architecture, most notably by decreasing the length and amount of lateral roots emerging from the primary root. Experimentation of mutant variants of
Arabidopsis thaliana ''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Orde ...

Arabidopsis thaliana
found that plants sense the Red to Far Red light ratio that enters the plant through photoreceptors known as
phytochrome phytochrome absorption spectrum (Devlin, 1969) Phytochromes are a class of photoreceptor protein, photoreceptor in plant Plants are mainly multicellular organisms, predominantly photosynthetic Photosynthesis is a process used by pla ...

phytochrome
s. Nearby plant leaves will absorb red light and reflect far- red light which will cause the ratio red to far red light to lower. The phytochrome PhyA that senses this Red to Far Red light ratio is localized in both the root system as well as the shoot system of plants, but through knockout mutant experimentation, it was found that root localized PhyA does not sense the light ratio, whether directly or axially, that leads to changes in the lateral root architecture. Research instead found that shoot localized PhyA is the phytochrome responsible for causing these architectural changes of the lateral root. Research has also found that phytochrome completes these architectural changes through the manipulation of auxin distribution in the root of the plant. When a low enough Red to Far Red ratio is sensed by PhyA, the phyA in the shoot will be mostly in its active form. In this form, PhyA stabilize the
transcription factor In molecular biology Molecular biology is the branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, molecular synthesis, modification, m ...
HY5 causing it to no longer be degraded as it is when phyA is in its inactive form. This stabilized transcription factor is then able to be transported to the roots of the plant through the
phloem Phloem (, ) is the living tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa d ...

phloem
, where it proceeds to induce its own transcription as a way to amplify its signal. In the roots of the plant HY5 functions to inhibit an auxin response factor known as ARF19, a response factor responsible for the translation of PIN3 and LAX3, two well known auxin transporting
protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...

protein
s. Thus, through manipulation of ARF19, the level and activity of
auxin Auxins (plural of auxin ) are a class of plant hormone Plant hormones (or phytohormones) are signal molecule In biology, cell signaling (cell signalling in British English), or cell-cell communication, governs the basic activities of cell (bio ...

auxin
transporters PIN3 and LAX3 is inhibited. Once inhibited, auxin levels will be low in areas where lateral root emergence normally occurs, resulting in a failure for the plant to have the emergence of the lateral root primordium through the root
pericycle The pericycle is a cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants. Although it is composed of non-vascular parenchyma cells, it's still considered part of the ...
. With this complex manipulation of Auxin transport in the roots, lateral root emergence will be inhibited in the roots and the root will instead elongate downwards, promoting vertical plant growth in an attempt to avoid shade. Research of Arabidopsis has led to the discovery of how this auxin mediated root response works. In an attempt to discover the role that
phytochrome phytochrome absorption spectrum (Devlin, 1969) Phytochromes are a class of photoreceptor protein, photoreceptor in plant Plants are mainly multicellular organisms, predominantly photosynthetic Photosynthesis is a process used by pla ...

phytochrome
plays in lateral root development, Salisbury et al. (2007) worked with ''
Arabidopsis thaliana ''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Orde ...

Arabidopsis thaliana
'' grown on agar plates. Salisbury et al. used wild type plants along with varying protein knockout and gene knockout Arabidopsis mutants to observe the results these mutations had on the root architecture, protein presence, and gene expression. To do this, Salisbury et al. used GFP fluorescence along with other forms of both macro and microscopic imagery to observe any changes various mutations caused. From these research, Salisbury et al. were able to theorize that shoot located phytochromes alter auxin levels in roots, controlling lateral root development and overall root architecture. In the experiments of van Gelderen et al. (2018), they wanted to see if and how it is that the shoot of ''
Arabidopsis thaliana ''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Orde ...

Arabidopsis thaliana
'' alters and affects root development and root architecture. To do this, they took Arabidopsis plants, grew them in agar gel, and exposed the roots and shoots to separate sources of light. From here, they altered the different wavelengths of light the shoot and root of the plants were receiving and recorded the lateral root density, amount of lateral roots, and the general architecture of the lateral roots. To identify the function of specific photoreceptors, proteins, genes, and hormones, they utilized various Arabidopsis knockout mutants and observed the resulting changes in lateral roots architecture. Through their observations and various experiments, van Gelderen et al. were able to develop a mechanism for how root detection of Red to Far-red light ratios alter lateral root development.


Types

A true root system consists of a primary root and secondary roots (or
lateral roots Lateral roots, emerging from the pericycle (meristematic tissue), extend horizontally from the primary root (radicle) and over time makeup the iconic branching pattern of root systems. They contribute to anchoring the plant securely into the soil, i ...
). * the diffuse root system: the primary root is not dominant; the whole root system is fibrous and branches in all directions. Most common in
monocots Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. The ...

monocots
. The main function of the fibrous root is to anchor the plant.


Specialized

The roots, or parts of roots, of many plant species have become specialized to serve adaptive purposes besides the two primary functions, described in the introduction. * Adventitious roots arise out-of-sequence from the more usual root formation of branches of a primary root, and instead originate from the stem, branches, leaves, or old woody roots. They commonly occur in
monocot Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. The ...
s and pteridophytes, but also in many
dicot The dicotyledons, also known as dicots (or more rarely dicotyls), are one of the two groups into which all the flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "a ...
s, such as
clover Clover or trefoil are common names for plants of the genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining ( ...

clover
(''Trifolium''),
ivy ''Hedera'', commonly called ivy (plural ivies), is a genus of 12–15 species of evergreen In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist ...

ivy
(''Hedera''),
strawberry The garden strawberry (or simply strawberry; ''Fragaria × ananassa'') is a widely grown hybrid species Hybrid speciation is a form of speciation Speciation is the evolution Evolution is change in the Heredity, heritable Phenotypi ...

strawberry
(''Fragaria'') and
willow Willows, also called sallows and osiers, from the genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining ( ...

willow
(''Salix''). Most aerial roots and stilt roots are adventitious. In some conifers adventitious roots can form the largest part of the root system. * Aerating roots (or knee root or knee or pneumatophores): roots rising above the ground, especially above water such as in some
mangrove A mangrove is a shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Pl ...

mangrove
genera (''
Avicennia ''Avicennia'' is a genus of flowering plants currently placed in the Acanthus (plant), bear's breeches family, Acanthaceae. It contains mangrove trees, which occur in the intertidal zones of Estuary, estuarine areas and are characterized by its "p ...
,
Sonneratia ''Sonneratia'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer t ...
''). In some plants like ''Avicennia'' the erect roots have a large number of breathing pores for exchange of gases. * : roots entirely above the ground, such as in ivy (''Hedera'') or in
epiphytic 200px, '' Tillandsia bourgaei'' growing on an oak tree in Mexico An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating a ...

epiphytic
orchid Orchidaceae ( ), commonly called the orchid family, is a diverse and widespread family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social ...

orchid
s. Many aerial roots are used to receive water and nutrient intake directly from the air - from fogs, dew or humidity in the air. Some rely on leaf systems to gather rain or humidity and even store it in scales or pockets. Other aerial roots, such as
mangrove A mangrove is a shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Pl ...

mangrove
aerial roots, are used for aeration and not for water absorption. Other aerial roots are used mainly for structure, functioning as prop roots, as in
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
or anchor roots or as the trunk in
strangler fig 210px, '' Ficus watkinsiana'' on ''Syzygium hemilampra'', Australia">Syzygium_hemilampra.html" ;"title="Ficus watkinsiana'' on ''Syzygium hemilampra">Ficus watkinsiana'' on ''Syzygium hemilampra'', Australia Strangler fig is the common name for a ...
. In some Epiphytes - plants living above the surface on other plants, aerial roots serve for reaching to water sources or reaching the surface, and then functioning as regular surface roots. * Canopy roots/arboreal roots: forms when tree branches support mats of epiphytes and detritus, which hold water and nutrients in the canopy. Tree branches send out canopy roots into these mats, likely to utilize the available nutrients and moisture. * Contractile roots: these pull bulbs or corms of
monocot Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. The ...
s, such as
hyacinth Hyacinth or Hyacinthus may refer to: Nature Plants * Hyacinth (plant), genus ''Hyacinthus'' ** ''Hyacinthus orientalis'', common hyacinth * Grape hyacinth, ''muscari'', a genus of perennial bulbous plants native to Eurasia * Hyacinth bean, ''labla ...
and
lily ''Lilium'' is a genus of Herbaceous plant, herbaceous flowering plants growing from bulbs, all with large prominent flowers. They are the true lilies. Lilies are a group of flowering plants which are important in culture and literature in much ...

lily
, and some
taproot A taproot is a large, central, and dominant root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants ...
s, such as
dandelion ''Taraxacum'' () is a large genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxono ...

dandelion
, deeper in the soil through expanding radially and contracting longitudinally. They have a wrinkled surface. * Coarse roots: roots that have undergone secondary thickening and have a woody structure. These roots have some ability to absorb water and nutrients, but their main function is transport and to provide a structure to connect the smaller diameter, fine roots to the rest of the plant. * Dimorphic root systems: roots with two distinctive forms for two separate functions * Fine roots: typically primary roots <2 mm diameter that have the function of water and nutrient uptake. They are often heavily branched and support mycorrhizas. These roots may be short lived, but are replaced by the plant in an ongoing process of root 'turnover'. * Haustorial roots: roots of parasitic plants that can absorb water and nutrients from another plant, such as in
mistletoe Mistletoe is the common name for obligate{{wiktionary, obligate As an adjective, obligate means "by necessity" (antonym '' facultative'') and is used mainly in biology in phrases such as: * Obligate aerobe 300px, Aerobic and anaerobic bacte ...

mistletoe
(''Viscum album'') and
dodder ''Cuscuta'' () (dodder) is a genus of over 201 species of yellow, orange, or red (rarely green) parasitic plant A parasitic plant is a plant that derives some or all of its nutritional requirement from another living plant. They make up about ...
. * Propagative roots: roots that form adventitious buds that develop into aboveground shoots, termed suckers, which form new plants, as in
Canada thistle ''Cirsium arvense'' is a perennial species of flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may ref ...
,
cherry A cherry is the fruit In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. ...

cherry
and many others. *
Proteoid root Proteoid roots of ''Leucospermum cordifolium'' Cluster roots, also known as proteoid roots, are plant roots that form clusters of closely spaced short lateral rootlets. They may form a two- to five-centimetre-thick mat just beneath the leaf litter. ...
s or cluster roots: dense clusters of rootlets of limited growth that develop under low
phosphate In chemistry, a phosphate is an anion, salt (chemistry), salt, functional group or ester derived from a phosphoric acids and phosphates, phosphoric acid. It most commonly means orthophosphate, a derivative of phosphoric acid, orthophosphoric a ...

phosphate
or low
iron Iron () is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...

iron
conditions in
Proteaceae The Proteaceae form a family (biology), family of flowering plants predominantly distributed in the Southern Hemisphere. The family comprises 83 genus, genera with about 1,660 known species. Together with the Platanaceae and Nelumbonaceae, they ...

Proteaceae
and some plants from the following families
Betulaceae Betulaceae, the birch family, includes six genera of deciduous In the fields of horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticu ...
,
Casuarinaceae The Casuarinaceae are a family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of families is to maintain ...

Casuarinaceae
,
Elaeagnaceae The Elaeagnaceae are a plant family, the oleaster family, of the order Rosales comprising small trees and shrubs, native to temperate regions of the Northern Hemisphere, south into tropical Asia and Australia. The family has about 60 species ...
,
Moraceae The Moraceae — often called the mulberry family or fig family — are a family of flowering plants comprising about 38 genera and over 1100 species. Most are widespread in tropical and subtropical regions, less so in temperate climates; however ...

Moraceae
,
Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...

Fabaceae
and
Myricaceae The Myricaceae are a small family of dicotyledonous shrubs and small trees in the order Fagales. There are three genera in the family, although some botanists separate many species from ''Myrica'' into a fourth genus ''Morella''. About 55 species ...
. * Stilt roots: these are adventitious support roots, common among
mangrove A mangrove is a shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Pl ...

mangrove
s. They grow down from lateral branches, branching in the soil. * Storage roots: these roots are modified for storage of food or water, such as
carrot The carrot (''Daucus carota'' subsp. ''sativus'') is a root vegetable, usually orange in color, though purple, black, red, white, and yellow cultivars exist. They are a domesticated form of the Daucus carota, wild carrot, ''Daucus carota'', ...

carrot
s and
beet The beetroot is the taproot A taproot is a large, central, and dominant root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into t ...
s. They include some
taproot A taproot is a large, central, and dominant root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants ...
s and tuberous roots. * Structural roots: large roots that have undergone considerable secondary thickening and provide mechanical support to woody plants and trees. * Surface roots: these proliferate close below the soil surface, exploiting water and easily available nutrients. Where conditions are close to optimum in the surface layers of soil, the growth of surface roots is encouraged and they commonly become the dominant roots. * Tuberous roots: fleshy and enlarged lateral roots for food or water storage, e.g.
sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledon The dicotyledons, also known as dicots (or more rarely dicotyls), are one of the two groups into which all the flowering plant The flowering plants, also known as Angio ...

sweet potato
. A type of storage root distinct from taproot.


Depths

The distribution of vascular plant roots within soil depends on plant form, the spatial and temporal availability of water and nutrients, and the physical properties of the soil. The deepest roots are generally found in deserts and temperate coniferous forests; the shallowest in tundra, boreal forest and temperate grasslands. The deepest observed living root, at least 60 metres below the ground surface, was observed during the excavation of an open-pit mine in Arizona, USA. Some roots can grow as deep as the tree is high. The majority of roots on most plants are however found relatively close to the surface where nutrient availability and aeration are more favourable for growth. Rooting depth may be physically restricted by rock or compacted soil close below the surface, or by anaerobic soil conditions.


Records


Evolutionary history

The fossil record of roots—or rather, infilled voids where roots rotted after death—spans back to the late
Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician The Ordovician ( ) is a geologic period A geological period is one of the several subdivisions of geologic time enabling cross-refere ...
, about 430 million years ago. Their identification is difficult, because casts and molds of roots are so similar in appearance to animal burrows. They can be discriminated using a range of features. The evolutionary development of roots likely happened from the modification of shallow
rhizomes Image:Lotus root.jpg, Nelumbo nucifera, Lotus rhizome peeled and sliced In botany and dendrology, a rhizome (, from grc, rhízōma, script=Latn (ῥίζωμα) - "mass of roots", from (ῥιζόω) "cause to strike root") is a modified subter ...
(modified horizontal stems) which anchored primitive vascular plants combined with the development of filamentous outgrowths (called
rhizoid Rhizoids are protuberances that extend from the lower epidermal cells of bryophyte Bryophytes are an informal group consisting of three divisions Division or divider may refer to: Mathematics *Division (mathematics) Division is one of th ...
s) which anchored the plants and conducted water to the plant from the soil.


Environmental interactions

Light has been shown to have some impact on roots, but its not been studied as much as the effect of light on other plant systems. Early research in the 1930s found that light decreased the effectiveness of
Indole-3-acetic acid Indole-3-acetic acid (IAA, 3-IAA) is the most common naturally occurring of the class. It is the best known of the auxins, and has been the subject of extensive studies by plant physiologists. IAA is a derivative of , containing a carboxymethyl ...
on adventitious root initiation. Studies of the pea in the 1950s shows that lateral root formation was inhibited by light, and in the early 1960s researchers found that light could induce positive
gravitropic Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant in response to gravity pulling on it. It also occurs in fungi. Gravity can be either "artificial gravity" or natural gravity. It is a general featur ...
responses in some situations. The effects of light on root elongation has been studied for
monocotyledonous Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. Th ...
and
dicotyledonous The dicotyledons, also known as dicots (or more rarely dicotyls), are one of the two groups into which all the flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte ...
plants, with the majority of studies finding that light inhibited root elongation, whether pulsed or continuous. Studies of ''
Arabidopsis ''Arabidopsis'' (rockcress) is a genus in the family Brassicaceae Brassicaceae () or Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the c ...

Arabidopsis
'' in the 1990s showed negative
phototropism File:Phototropism Diagram.svg, thumbnail, Auxin distribution controls phototropism. 1. Sunlight strikes the plant from directly above. Auxin (pink dots) encourages growth straight up. 2, 3, 4. Sunlight strikes the plant at an angle. Auxin is conc ...

phototropism
and inhibition of the elongation of root hairs in light sensed by
phyB Phytochromes are a class of photoreceptor in plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, thro ...
. Certain plants, namely
Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...

Fabaceae
, form
root nodules Root nodules are found on the root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller ...
in order to associate and form a symbiotic relationship with nitrogen-fixing bacteria called
rhizobia '' bacteria Rhizobia are diazotrophic bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a ...

rhizobia
. Owing to the high energy required to fix nitrogen from the atmosphere, the bacteria take carbon compounds from the plant to fuel the process. In return, the plant takes nitrogen compounds produced from ammonia by the bacteria. Soil temperature is a factor that effects root initiation and length. Root length is usually impacted more dramatically by temperature than overall mass, where cooler temperatures tend to cause more lateral growth because downward extension is limited by cooler temperatures at subsoil levels. Needs vary by plant species, but in temperate regions cool temperatures may limit root systems. Cool temperature species like
oats The oat (''Avena sativa''), sometimes called the common oat, is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A spec ...

oats
,
rapeseed Rapeseed (''Brassica napus ''subsp.'' napus''), also known as rape, or oilseed rape, is a bright-yellow flowering member of the family Brassicaceae Brassicaceae () or Cruciferae () is a medium-sized and economically important family ...

rapeseed
,
rye Rye (''Secale cereale'') is a grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants known as grasses. It includes the cereal grasses, bamboo Bamboos are a diverse group of ev ...

rye
,
wheat Wheat is a grass widely cultivated for its seed, a cereal grain which is a worldwide staple food. The many species of wheat together make up the genus ''Triticum''; the most widely grown is common wheat Common wheat (''Triticum aestivum'' ...

wheat
fare better in lower temperatures than summer annuals like
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
and
cotton Cotton is a soft, fluffy staple fiber Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of s ...

cotton
. Researchers have found that plants like cotton develop wider and shorter
taproot A taproot is a large, central, and dominant root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants ...
s in cooler temperatures. The first root originating from the seed usually has a wider diameter than root branches, so smaller root diameters are expected if temperatures increase root initiation. Root diameter also decreases when the root elongates.Encyclopedia of Soil Science
/ref>


Plant interactions

Plants can interact with one another in their environment through their root systems. Studies have demonstrated that plant-plant interaction occurs among root systems via the soil as a medium. Researchers have tested whether plants growing in ambient conditions would change their behavior if a nearby plant was exposed to drought conditions. Since nearby plants showed no changes in
stoma File:LeafUndersideWithStomata.jpg, The underside of a leaf. In this species (''Tradescantia zebrina'') the guard cells of the stomata are green because they contain chlorophyll while the epidermal cells are chlorophyll-free and contain red pigme ...

stoma
tal aperture researchers believe the drought signal spread through the roots and soil, not through the air as a volatile chemical signal.


Soil interactions

Soil microbiota can suppress both disease and beneficial root symbionts (mycorrhizal fungi are easier to establish in sterile soil). Inoculation with soil bacteria can increase internode extension, yield and quicken flowering. The migration of bacteria along the root varies with natural soil conditions. For example, research has found that the root systems of wheat seeds inoculated with ''
Azotobacter ''Azotobacter'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer ...
'' showed higher populations in soils favorable to Azotobacter growth. Some studies have been unsuccessful in increasing the levels of certain microbes (such as '' P. fluorescens'') in natural soil without prior sterilization. Grass root systems are beneficial at reducing
soil erosion Soil erosion is the displacement of the upper layer of soil File:Stagnogley.JPG, Surface-water-Gley soil, gley developed in glacial till, Northern Ireland. Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that togeth ...

soil erosion
by holding the soil together.
Perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, thr ...
grasses that grow wild in rangelands contribute organic matter to the soil when their old roots decay after attacks by beneficial
fungi A fungus (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full ...

fungi
,
protozoa Protozoa (singular protozoon or protozoan, plural protozoa or protozoans) is an informal term for a group of single-celled eukaryote Eukaryotes () are organism In biology, an organism () is any organic, life, living system that ...

protozoa
, bacteria, insects and worms release nutrients. Scientists have observed significant diversity of the microbial cover of roots at around 10 percent of three week old root segments covered. On younger roots there was even low coverage, but even on 3 month old roots the coverage was only around 37%. Before the 1970s, scientists believed that the majority of the root surface was covered by microorganisms.


Nutrient absorption

Researchers studying
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
seedlings found that calcium absorption was greatest in the
apical Apical means "pertaining to an Apex (disambiguation), apex". It may refer to: *Apical ancestor, refers to the last common ancestor of an entire group, such as a species (biology) or a clan (anthropology) *Apical (anatomy), an anatomical term of loc ...
root segment, and potassium at the base of the root. Along other root segments absorption was similar. Absorbed potassium is transported to the root tip, and to a lesser extent other parts of the root, then also to the shoot and grain. Calcium transport from the apical segment is slower, mostly transported upward and accumulated in stem and shoot. Researchers found that partial deficiencies of K or P did not change the
fatty acid In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...
composition of phosphatidyl choline in '' Brassica napus L.'' plants. Calcium deficiency did, on the other hand, lead to a marked decline of
polyunsaturated In nutrition Nutrition is the biochemical Biochemistry or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided ...
compounds that would be expected to have negative impacts for integrity of the plant
membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecule A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A m ...

membrane
, that could effect some properties like its permeability, and is needed for the
ion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ...
uptake activity of the root membranes.


Economic importance

The term
root crop Root vegetables are underground plant parts eaten by humans as food Food is any substance consumed to provide Nutrient, nutritional support for an organism. Food is usually of plant, animal or Fungus, fungal origin, and contains essential n ...
s refers to any edible underground plant structure, but many root crops are actually stems, such as
potato The potato is a starch#Food, starchy tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial plant, perennial in the nightshade family Solanaceae. Wild potato species can be found thro ...

potato
tubers. Edible roots include
cassava ''Manihot esculenta'', commonly called cassava (), manioc, or yuca (among numerous regional names) is a woody shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a pla ...

cassava
,
sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledon The dicotyledons, also known as dicots (or more rarely dicotyls), are one of the two groups into which all the flowering plant The flowering plants, also known as Angio ...

sweet potato
,
beet The beetroot is the taproot A taproot is a large, central, and dominant root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into t ...
,
carrot The carrot (''Daucus carota'' subsp. ''sativus'') is a root vegetable, usually orange in color, though purple, black, red, white, and yellow cultivars exist. They are a domesticated form of the Daucus carota, wild carrot, ''Daucus carota'', ...

carrot
,
rutabaga Rutabaga (; North American English) or swede (British English and some Commonwealth English) is a root vegetable, a form of ''Brassica napus'' (which also includes rapeseed). Other names include Swedish turnip, neep (Scottish) and Turnip (term ...

rutabaga
,
turnip The turnip or white turnip (''Brassica rapa ''Brassica rapa'' is a plant Plants are mainly multicellular organisms, predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transforma ...

turnip
,
parsnip The parsnip (''Pastinaca ''Pastinaca'' (parsnips) is a genus of flowering plant in the family Apiaceae, comprising 14 species. Economically, the most important member of the genus is ''Pastinaca sativa'', the parsnip. Etymology The etymolo ...

parsnip
,
radish The radish (''Raphanus raphanistrum ''Raphanus raphanistrum'', the sea radish, wild radish, white charlock or jointed charlock, is a flowering plant in the family Brassicaceae. One of its subspecies, ''Raphanus raphanistrum'' subsp. ''sativ ...

radish
, yam and
horseradish Horseradish (''Armoracia rusticana'', syn. ''Cochlearia armoracia'') is a perennial plant of the family Brassicaceae (which also includes Mustard plant, mustard, wasabi, broccoli, cabbage, and radish). It is a root vegetable, cultivated and us ...

horseradish
. Spices obtained from roots include
sassafras ''Sassafras'' is a genus of three extant Extant is the opposite of the word extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to b ...

sassafras
,
angelica 220px, Wild angelica (''Angelica sylvestris'') from Thomé, ''Flora von Deutschland, Österreich und der Schweiz'' 1885 ''Angelica'' is a genus of about 60 species of tall Biennial plant, biennial and Perennial plant, perennial herbaceous, herbs ...

angelica
,
sarsaparillaSarsaparilla often refers to the sarsaparilla (soft drink), sarsaparilla soft drink, made from Smilax plants. Sarsaparilla may also refer to: Biology *Several species of plants, of the genus ''Smilax'', including: **''Smilax ornata'', also known a ...
and
licorice Liquorice ( UK) or licorice ( US) ( ; also ) is the common name Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common Boston Common (also known as the Common) is a central public park in dow ...

licorice
.
Sugar beet A sugar beet is a plant whose root contains a high concentration of sucrose Sucrose is a type of sugar Sugar is the generic name for Sweetness, sweet-tasting, soluble carbohydrates, many of which are used in food. Table sugar, granulated ...
is an important source of sugar. Yam roots are a source of
estrogen Estrogens or oestrogens, are a class of natural or synthetic s responsible for the development and regulation of the female and s. There are three major estrogens that have estrogenic hormonal activity: (E1), (E2), and (E3). Estradiol, an ...

estrogen
compounds used in
birth control pill The combined oral contraceptive pill (COCP), often referred to as the birth control pill or colloquially as "the pill", is a type of birth control Birth control, also known as contraception, anticonception, and fertility control, is a meth ...
s. The fish
poison In biology, poisons are Chemical substance, substances that can cause death, injury or harm to organs, Tissue (biology), tissues, Cell (biology), cells, and DNA usually by chemical reactions or other activity (chemistry), activity on the molecul ...

poison
and
insecticide Insecticides are substances used to kill insect Insects (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from ...
rotenone Rotenone is an odorless, colorless, crystalline isoflavone used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the seeds and stems of several plants, such as the jicama vine plant, and the roots of several member ...

rotenone
is obtained from roots of ''
Lonchocarpus ''Lonchocarpus'' is a plant genus in the legume family (biology), family (Fabaceae). The species are called lancepods due to their fruit resembling an ornate lance tip or a few beads on a string. ''Cubé'' resin is produced from the roots of ''L ...
'' spp. Important medicines from roots are
ginseng Image:Insam (ginseng).jpg, 330px, A root of cultivated Korean ginseng ''(P. ginseng)'' Ginseng () is the root of plants in the genus ''Panax'', such as Korean ginseng (''Panax ginseng, P. ginseng''), South China ginseng (''Panax notoginseng, P. not ...

ginseng
, aconite,
ipecac Syrup of ipecac (), commonly referred to as ipecac, is a drug that was once widely used as an expectorant Mucoactive agents are a class of chemical agents which aid in the clearance of mucus Mucus ( ) is a slippery aqueous secretion produced ...
,
gentian ''Gentiana'' is a genus of flowering plants belonging to the gentian family (biology), family (Gentianaceae), the tribe Gentianeae, and the Monophyly, monophyletic subtribe Gentianinae. With about 400 species it is considered a large genus. They ...

gentian
and
reserpine Reserpine is a drug that is used for the treatment of high blood pressure Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term Disease, medical condition in which the blood pressure in the artery, arteries is per ...

reserpine
. Several legumes that have nitrogen-fixing root nodules are used as green manure crops, which provide nitrogen fertilizer for other crops when plowed under. Specialized
bald cypress ''Taxodium distichum'' (bald cypress, swamp cypress; french: cyprès chauve; ''cipre'' in Louisiana_French, Louisiana) is a deciduous Pinophyta, conifer in the family Cupressaceae. It is native to the southeastern United States. Hardy and tough, ...

bald cypress
roots, termed knees, are sold as souvenirs, lamp bases and carved into folk art.
Native Americans Native Americans may refer to: Ethnic groups * Indigenous peoples of the Americas, the pre-Columbian peoples of North and South America and their descendants * Native Americans in the United States * Indigenous peoples in Canada, the indigenous p ...
used the flexible roots of
white spruceWhite spruce is a common name for several species of spruce ('' Picea'') and may refer to: * ''Picea glauca'', native to most of Canada and Alaska with limited populations in the northeastern United States * '' Picea engelmannii'', native to the R ...

white spruce
for basketry.
Tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only wood plants with se ...

Tree
roots can heave and destroy
concrete Concrete is a composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material Material is a substance Substance may refer to: * Substance (Jainism), a ter ...

concrete
sidewalks and crush or clog buried pipes.Zahniser, David (February 21, 2008
"City to pass the bucks on sidewalks?"
''
Los Angeles Times The ''Los Angeles Times'' (abbreviated as ''LA Times'') is a daily newspaper A newspaper is a containing written and is often typed in black ink with a white or gray background. Newspapers can cover a wide variety of fields such as , ...

Los Angeles Times
''
The aerial roots of
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have damaged ancient
Mayan Mayan most commonly refers to: * Maya peoples, various indigenous peoples of Mesoamerica and northern Central America * Maya civilization, pre-Columbian culture of Mesoamerica and northern Central America * Mayan languages, language family spoken i ...
temple A temple (from the Latin ) is a building reserved for spiritual rituals and activities such as prayer and sacrifice. Religions which erect temples include Christianity (whose temples are typically called church (building), churches), Hinduism (w ...

temple
s in
Central America Central America ( es, América Central, , ''Centroamérica'' ) is a region of the Americas The Americas (also collectively called America) is a landmass comprising the totality of North North is one of the four compass points or ...

Central America
and the temple of
Angkor Wat Angkor Wat (; km, អង្គរវត្ត "Temple city/city of temples") is the largest religious structure (temple complex) in the world by land area, measuring , located in Cambodia. Originally constructed as a personal mausoleum for ...

Angkor Wat
in
Cambodia Cambodia (; also Kampuchea ; km, កម្ពុជា, ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese peninsula in Southeast Asia. It is in area, bordered by Thailand to Cambodia–T ...

Cambodia
. Trees stabilize soil on a slope prone to
landslides The term landslide or, less frequently, landslip refers to several forms of mass wasting Mass wasting, also known as slope movement or mass movement, is the geomorphic process by which soil Soil (often stylized as SOiL) is an American roc ...
. The
root hair Root hair, or absorbent hairs, are outgrowths of epidermal cells, specialized cells at the tip of a plant root In vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τρα ...
s work as an anchor on the soil.
Vegetative propagation '' Bryophyllum daigremontianum'' produces plantlets along the margins of its leaves. When they are mature enough, they drop off and root in any suitable soil beneath. Vegetative reproduction (also known as vegetative propagation, vegetative ...
of plants via cuttings depends on adventitious root formation. Hundreds of millions of plants are propagated via cuttings annually including
chrysanthemum Chrysanthemums (), sometimes called mums or chrysanths, are flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Gree ...

chrysanthemum
,
poinsettia The poinsettia ( or ) (''Euphorbia pulcherrima'') is a commercially important plant species of the diverse spurge family ( Euphorbiaceae). Indigenous to Mexico and Central America, the poinsettia was first described by Europeans in 1834. It is ...

poinsettia
,
carnation ''Dianthus caryophyllus'', commonly known as the carnation or clove pink, is a species of ''Dianthus''. It is probably native to the Mediterranean region but its exact range is unknown due to extensive cultivation for the last 2,000 years.Med-C ...

carnation
, ornamental
shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the p ...

shrub
s and many
houseplants A houseplant is a plant that is grown indoors in places such as House, residences and offices, namely for decorative purposes, but studies have also shown them to have positive psychological effects. They also help with indoor air purification, sin ...

houseplants
. Roots can also protect the environment by holding the soil to reduce soil erosion. This is especially important in areas such as
sand dunes A dune is a landform A landform is a natural or artificial feature of the solid surface of the Earth or other planetary body A planet is an astronomical body Astronomy (from el, ἀστρονομία, literally meaning the sc ...

sand dunes
.


See also

*
Absorption of waterIn higher plants water is absorbed through root hairs which are in contact with soil water and from a root hair zone a little the root tips Active absorption Active absorption refers to the absorption of water by roots with the help of adenosine t ...
*
Cypress knee Cypress is a common name for various coniferous trees or shrubs of northern temperateness, temperate regions that belong to the family Cupressaceae. The word ''cypress'' is derived from Old French ''cipres'', which was imported from Latin ''cypre ...
* Drought rhizogenesis *
Fibrous root system A fibrous root system is the opposite of a taproot A taproot is a large, central, and dominant root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and ...
*
Mycorrhiza A mycorrhiza (from Ancient Greek, Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, mycorrhiza or mycorrhizas) is a mutual symbiosis, symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role ...

Mycorrhiza
– root symbiosis in which individual hyphae extending from the mycelium of a fungus colonize the roots of a host plant. *
Mycorrhizal network Mycorrhizal networks (also known as common mycorrhizal networks or CMN) are underground hyphal networks created by mycorrhizal fungi that connect individual plants together and transfer water, carbon, nitrogen, and other nutrients and minerals. ...

Mycorrhizal network
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Plant physiology Plant physiology is a subdiscipline of botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. ...

Plant physiology
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Rhizosphere The rhizosphere is the narrow region of soil Soil (often stylized as SOiL) is an American rock band that was formed in Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interactive maps of Chic ...

Rhizosphere
– region of soil around the root influenced by root secretions and microorganisms present *
Root cutting stem cutting has been coaxed to form new roots, and is now a complete plant. A plant cutting is a piece of a plant that is used in horticulture for vegetative reproduction, vegetative (asexual) plant propagation, propagation. A piece of the Plant st ...
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Stolon In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms ...
* Tanada effect *
Taproot A taproot is a large, central, and dominant root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants ...


References


Further reading

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External links


Botany – University of Arkansas at Little Rock
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